When I write an email, how should I sign this? For a formal letter, it feels too informal and a little bit redundant to sign with just my first name, and very redundant (because of the signature field) to sign with my first and last name:

4 Answers
4

Professors and the like have been reading emails for long enough that I bet they know these two conventions that you seem to indicate you're unsure of:

Emails, being not letters, contain who they are from in their
headers. Email readers display this to the recipient in the way in
which the recipient is likely most accustomed to by now.

Emails may, or may not, have a signature block at the end.
This block is separated from the content by a line of text
consisting of only "-- " (dash dash space). A good email reader
will format, color, or highlight this block differently. A
heavy email user will ignore it.

So right off the bat, you're doing it wrong with how you delimit your signature. Secondly this block should be ignored by the person reading it, unless they're looking for some information they haven't seen in the email or the headers (your address, where, yes, it's okay to repeat your name). Often this is ignored because people once generated them per email with quotes of the day, famous sayings, bible bits etc. thus they're totally about expressing personal tastes. When you assume they're ignored, there's no duplicate information in them to worry about; they're entirely redundant.

When writing formally with an opening and closing as though it were a formal letter, yes, you will say "Dear Your Name" [redundant because the name is in the to header] and "Sincerely My Name" [redundant because your name is in the from header], and in countries like Ireland, Switzerland, Germany etc. where certain signed information is mandatory, there will be a standardized sig block.

If you hate redundancy, then left it off, as you described. You can separate the name from the address, so it looks a little bit more "friendly":

Sincerely,

John Doe

Acme Widget Company
123 Elm Street
Metropolis, USA

You can also ask yourself, if you really need a signature. Some laws require them for companies (at least here in Germany), but according to your sample content, I assume you do not need the company name in there. I don't think you need a full signature just for asking your professor for help. Your name should suffice.

Do you have the option of turning the signature block off on an individual email? that would solve the redundancy problem.

You can also style your sig block so that it's obviously autogenerated (different color, smaller size), and then sign with your first name. I have seen people just sign with "sincerely" because their name is in the sig block, but I personally find that a little lazy.

Informal emails I either don't sign or I sign with my initials. (which then occasionally leads to response emails addressed to my initials ["Dear LGI,"], which I find amusing.)